Method of making an electrical switch sub-assembly



Feb. 4, 1969 R. BERGER 3,425,122

METHOD OF MAKING AN ELECTRICAL SWITCH SUB-ASSEMBLY Filed Jan. 14, 1965 Sheet of 2 PIC-{.20.

IN VE N TOR Richard Berger ATTORNE Y5 Feb. 4,1969 R. BERGER 3,425,122

METHOD OF MAKING AN ELECTRICAL SWITCH SUB-ASSEMBLY Filed Jan. 14, 1965 Sheet 2 of 2 FIG.4. FIG. 5.

INVENTOR Richard Berger BYW/E/ ATTORNE Y5 United States Patent 3,425,122 METHOD OF MAKING AN ELECTRICAL SWITCH SUB-ASSEMBLY Richard Berger, Wunstorf, Germany, assignor to Telefunken Patentverwertungs-G.m.b.H., Ulm (Danube), Germany Filed Jan. 14, 1965, Ser. No. 425,592 Claims priority, application Germany, Feb. 1, 1964,

US. or. 29-622 6 Claims Int. (:1. H01h 11/00, 19/10; B29f 1/10 ABSTRACT OF THE DISCLOSURE A slide-type switch having a slide made of insulating material and carrying metal contact elements sandwiched and movable between two rows of flexible stationary contact elements. Two contact assemblies, each containing one row of stationary contact elements, are made by arranging metal wires in an insulator and stamping the extending ends of each wire to form a contact surface. The two contact assemblies are placed parallel to each other with a slide sandwiched therebetween.

pieces, generally made of sheet metal, which are carried by a slide, so that the particular stationary contacts which are electrically contacted will depend on the position of the slide. Such switches are made as follows. First, the stationary contacts are stamped out of sheet metal and are then bent to have the desired configuration. The individual contacts are then set into plates, for example, printed circuit plates, or they are attached to strips or the like. Setting in prefabricated contacts is an expensive proposition since it generally has to be done by hand. Furthermore, there is always the danger, inherent in the manual assembly, that the contacts will be bent out of the desired shape or that they will not be properly positioned which, in turn, usually makes it necessary to adjust the contacts after they have been put in place. This, experience has shown, is very difiicult, and, especially in the case of miniature components, is often not practicable at all because the contacts next tothe contact to be adjusted will often make it impossible for adjusting tools to be placed on the part. All in all, the positioning and adjustment of contacts can, especially in mass production, be considered to pose very reat problems.

It is, therefore, the primary object of the present invention to provide a way in which switches of the above type can be manufactured so as to avoid the above-described drawbacks, namely, to provide a method for making switches, and especially slide-type switches, wherein there are a plurality of adjacent contacts. Accordingly, the present invention resides, basically, in a method of making a contact assembly wherein a plurality of contacts, each having a desired shape, are arranged next to each other, which method comprises the steps of making an intermediate product comprising an insulating strip carrying 3,425,122 Patented Feb. 4, 1969 a plurality of generally parallel, spaced apart wires which are transverse to the insulating strip and extend from both sides thereof, and thereafter stamping one of the two extending ends of each wire for imparting the desired shape thereto.

According to a further feature of the invention, the intermediate product is made by positioning. a plurality of wires, of intermediate lengths, in parallel spaced relationship, securing to the wires transverse insulating strips which are spaced from each other a distance corresponding to the length of the wires of the intermediate product, and severing the wires along lines which are transverse to the wires and generally parallel with and between consecutive strips, thereby to obtain the intermediate products.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a plan view showing one of a plurality of wires, of indeterminate length, together with insulating strips already secured thereto.

FIGURE la is a side view of the arrangement shown in FIGURE 1, and additionally shows the apparatus for carrying out the process of the present invention.

FIGURE 2 is a plan view of the intermediate product derived from the arrangement shown in FIGURES 1 and 1a.

FIGURE 2a is an end view of the product shown in FIGURE 2.

FIGURE 3 is a fragmentary front elevational view of a contact assembly made in accordance with the present invention.

FIGURE 3a is a side elevational view of the contact assembly of FIGURE 3, and additionally shows stamping means.

FIGURE 4 is a side elevational view showing a composite contact assembly incorporating two of the contact assemblies of FIGURES 3;"ain-d 30.

FIGURE 5 is a side elevational view, partly in section,

showing a slide-type switch incorporating the compositecontact assembly of FIGURE 4.

Referring now to the drawings and first to FIGURES l and 1a thereof in particular, the same show a plurality of wires 1 which are played olf suitable supply rolls, one of whrich is shown at 10 in FIGURE 1a. The wires 1 have series of transverse plastic strips 2 molded to them. The molding operation can be carried out in any one of which is shown at 10 in FIGURE la. The wires molding machine shown schematically in FIGURE 1a at 11, and need therefore not be described in detail. This molding may be carried out continuously or in a step-wise manner.

Next, the wires 1 are cut along transverse lines 3, such as by means of suitable knives 12 (FIGURE 1a), so as to produce a plurality of individual contact assemblies. One such contact assembly is depicted in FIGURES 2 and 2a 'which show the assembly as comprising one strip 2 through which pass a plurality of wires 1. The wires extend longitudinally beyond both sides of the strip 2 to the ends 4 and 5. The ends 5 may, for instance, serve as lead-ins, for example, by inserting the contact assembly into appropriately configured printed circuit boards.

The next manufacturing step is that of imparting to the wires the ultimate configuration which the stationary contacts are to have. This is done by means of suitable stamps or dies 13, 13a, so that each contact will be given the configuration shown, for example, in FIGURES 3 and 3a which illustrate each contact as having a longitudinal flat portion 6 and a calotte-shaped end portion 7. The flat portion 6 serves to impart the desired resilient characteristics to the contact while the part 7 is the part which comes into actual physical contact with the slide or other elements, i.e., the part at whcih the contact is to be electrically engaged.

FIGURE 4 shows a composite contact assembly made of two contact assemblies each as depicted in FIGURES 3 and 3a. The two plastic strips 2 are glued or otherwise suitably secured together so that the two calotte-shaped parts 7 ofopposite contacts resiliently engage each other.

FIGURE shows the composite contact assemblyof FIGURE 4 in conjunction with a slide :8, made of insulating material and carrying metallic coatings 8a which make electrical contact with the respective stationary contacts.

In practice, there will be provided a suitable dust cover such as a cap 9 made, for example, of transparent plastic.

It will be seen from the above that, in accordance with the present invention, the process for making the contact assembly as shown in FIGURES 3 and -3a comprises the steps of first making the intermediate product shown in FIGURES 2 and 2a, namely, an insulating strip 2 carrying a plurality of generally parallel, spaced apart wires 11 positioned transversely to the insulating strip and extending from both sides thereof, and then stamping one of the two extending ends of each wire, e.g., the end 4, for imparting the desired shape thereto. This, it will be appreciated, allows the contacts themselves to be made from simple starting materials, namely, wires. Once the contact assemblies are finished, the individual contacts require no adjustment because they are given their ultimate shape during the stamping step, after having first been firmly secured to the insulating strips. This, then, eliminates the need for any manual adjustment which, as explained above, is particularly difficult in the case of miniature components.

While, in most instances, molding the strips onto the wires has been found to be the most practical way of securing the strips and wires to each other in such a way as to provide a firm seating for the wires in the strips, it may at times be advantageous to prefabricate the strips and thereafter to press, wedge or glue the strips and wires to each other, e.g., the strips may be provided with suitably positioned grooves into which the wires may be pressed.

In practice, the surfaces of the wires will be silvercoated so as to provide good contact-making characteristics.

The insulating strips 2 need not necessarily be rectilinear, inasmuch as, if the contact assembly is to be used in a rotary switch, the strip will be ring-shaped or arcuate. In that case, the wires will not be co-planar with each other but will be arranged along the envelope of a cylinder.

It will also be seen from the above that the intermediate product depicted in FIGURES 2 and 2a may be made by positioning a plurality of wires, of indeterminate lengths, in parallel spaced relationship, by then securing to the wires transverse insulating strips which are spaced from each other a distance corresponding to the length of the wires of the intermediate product, and finally severing the wires along lines (rectilinear lines in the case of fiat contact assemblies and circular lines in the case of annular or segment-shaped contact assemblies) which are transverse to the wires and generally parallel with and between consecutive insulating strips, thereby to obtain the intermediate products.

Only after the intermediate products are thus obtained will the ends of the wires be subjected to the stamping operation. The advantage of this is that there will at no time be any loose, small pieces of wire, inasmuch as the wires, while they were still in their indeterminate length, were secured to the strips so that the smallest individual component to be handled will be the intermediate product shown in FIGURES 2 and 2a. This eliminates the likelihood of losing any parts and hence reduces waste. Also, the stamping process increases the elasticity of the contacts so that the starting material can be relatively soft wire.

It will also be seen from the above that, in accordance with the present invention, there is provided a composite contact assembly which is made by placingtwo contact assemblies, each as depicted in FIGURES 3 and hand made by the above-described process, next to each other such that insulating strips of the respective contact assemblies are parallel to each other, the strips being secured to each other. There thus may be obtained a slide-type switch which comprises the composite contact assembly,

.as well as the metallic contact means 8a shown in FIG- URE 5, which are arranged between contacts of the respective contact assemblies. In this way, the contact pressure of all of the individual contacts can be adjusted very precisely and evenly in one operation.

In practice, the strips 2 will be dimensioned, and/or the contacts 6, 7, will, during the stamping operation, be so oriented, that when the insulating strips of two contact assemblies are placed against each other, the contactmaking ends of the coating contacts will engage each other, or the contacts of a slide, with the proper contact pressure.

It will be understod that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. A method of making a slide-type switch having a movable slide, made of insulating material and carrying metal contact elements, between two rows of stationary contact elements, said method comprising the steps of:

(a) making an intermediate product comprising an insulating strip carrying a plurality of generally parallel, spaced apart wires, in a single row, said wires being transverse to the insulating strip and longitudinally extending beyond both sides thereof;

(b) stamping one of the two extending portions of each wire for flattening the same along its longitudinal axis to alter its resilient characteristics and for shap ing laterally to said axis the portion nearest its end into a convex contact surface;

(c) placing two contact assemblies, each made by the steps defined in steps (a) and (b), next to each other with the insulating strips of the respective contact assemblies. parallel to each other; and

(d) securing said insulating strips together.

2. A method as defined in claim 1 wherein said step (a) comprises the steps of:

(l) positioning a plurality of wires 'of indeterminate lengths, in parallel spaced relationship; I,

(2 securing to said wires transverse insulating strips, said strips being spaced from each other a distance corresponding'to the length of the wires of said intermediate product; and v I (3) severing the wires along lines which are transverse to said wires and generally parallel with and between consecutive strips, thereby to obtain said intermediate products. v l

3. A method as defined in claim Z wherein said insulating strips are molded onto said wires.

4. A method as defined in claim 2 wherein said insulating strips are molded about said wires thereby to encompass each wire throughout a portion of its length.

' 5. A method as defined in claim Z wherein said insulating strips and said wires are pressed together.

6. A method as defined in claim 1 wherein each of said wires, during said step (b) has imparte to it a calotte-shaped contact-making portion.

(References on following page) References Cited UNITED STATES PATENTS Heibel 317101 Cihlar et a1. 29-.155.5 Seele 264261 Johnson 29--155.5 Stevens 29--155.5 Leeuwen 200166.1 XR Krone.

6 FOREIGN PATENTS 3/1960 Canada. 6/ 1959 Great Britain.

5 JOHN F. CAMPBELL, Primary Examiner.

R. W. CHURCH, Assistant Examiner.

US. Cl. X.R.

29--417, 630; 72360; 76-104; ZOO-11, 166; 10 264272; 317112 

